Computer systems inherently have limited resources, particularly CPU resources. These limited resources must be allocated among the different applications operating within the system. A prior allocation mechanism for allocating system resources to applications is a system known as Process Resource Manager (PRM) 10 as shown in FIG. 1A. It is used to partition the CPU resource 11 and various other resources among the different applications 12, 13, 14. The PRM partitions the resources into fractions of the whole, which are expressed as percentages in PRM configuration, as shown in FIG. 1B. The fractions or pieces are then assigned to groups of processes, which comprise applications. Each application would then receive some portion of the available resources.
The PRM is a static mechanism, meaning that the allocation configuration is fixed by an administrator, and can only be changed by an administrator. In other words, the administrator specifies where the partitions should lie, i.e., what percent of the machine goes to application 12, application 13, and application 14. This information is fixed, so it cannot respond to changes in the needs of the different applications. For example, one application may be mostly idle, but occasionally has a large amount of work to do. Under the static mechanism with fixed entitlements, this application would be allocated a smaller fraction of the CPU resources, as a larger fraction can not be justified because of the large amount of idle time. Consequently, when the large amount of work is received, then the application's performance will suffer because of its low entitlement. Therefore, the transactions will take longer to process. Another example is where a transaction requires large amounts of resources for extended periods of time, but also has periods of idle time. Under the static mechanism with fixed entitlements, this application would be allocated a larger fraction of the CPU resources. Consequently, when this application is idle, other applications' performances will suffer, as this application is assigned a large amount of resources that are not being used, and thus are not available for other applications. Therefore, the other transactions will take longer to process. Thus, this mechanism cannot handle changes in the requirements of the different applications.
Another problem is the partitioning of the resources by the administrator. The administrator has to think in terms of the actual machine resources and the requirements of the different applications. This is problematic because the resources and applications are operating at a lower level than what a person typically views. Moreover, the administrator has to have a great deal of knowledge of the application's characteristics and its resource requirements in order to determine where to set the partitions. Lack of knowledge is typically made up with guesswork. For example, an administrator may choose to set application 13 at 20% of the CPU resources. If the users of the system complain, the administrator may change the value later on.
An alternative mechanism is taught in U.S. Pat. No. 5,675,739 by IBM, which is hereby incorporated by reference. The IBM mechanism uses a priority-based model to process applications. In other words, high priority applications are serviced from a queue before lower priority applications. This mechanism can change the priorities to adjust processing performance.
Such prior art mechanisms are also ineffective for multiple partition systems. Large computer systems, e.g. those with multiple processors, multiple I/O resources, multiple storage resources, etc., can be separated into partitions or protected domains. These partitions are hardware separations that place resources into separate functional blocks. Resources in one block do not have direct access to resources in another block. This prevents one application from using the entire system resources, as well as contains faults and errors. However, the partitions, once defined, are static in nature, and cannot be readily changed without operator intervention. Thus, resources cannot be readily moved from one partition to another to satisfy workload balancing.